Picobubble Enhanced Fine Coal Flotation

Abstract

Froth flotation is widely used in the coal industry to clean ?28 mesh fine coal. A successful recovery of particles by flotation depends on efficient particle‐bubble collision and attachment with minimal subsequent particle detachment from bubble. Flotation is effective in a narrow size range beyond which the flotation efficiency drops drastically. It is now known that the low flotation recovery of particles in the finest size fractions is mainly due to a low probability of bubble‐particle collision while the main reason for poor coarse particle flotation recovery is the high probability of detachment. A fundamental analysis has shown that use of picobubbles can significantly improve the flotation recovery of particles in a wide range of size by increasing the probability of collision and attachment and reducing the probability of detachment.

A specially designed column with a picobubble generator has been developed for enhanced recovery of fine coal particles. Picobubbles were produced based on the hydrodynamic cavitation principle. They are characterized by a size distribution that is mostly below 1 µm and adhere preferentially to the hydrophobic surfaces. The presence of picobubbles increases the probability of collision and attachment and decreases the probability of detachment, thus enhancing flotation recovery. Experimental results with the Coalberg seam coal in West Virginia, U.S.A. have shown that the use of picobubbles in a 2″ column flotation increased fine coal recovery by 10–30%, depending on the feed rate, collector dosage, and other flotation conditions. Picobubbles also acted as a secondary collector and reduced the collector dosage by one third to one half.     

从煤泥中回收精煤的高效旋流微泡浮选柱技术

介绍了旋流微泡浮选柱与传统机械搅拌浮选机的性能对比 ,旋流微泡浮选柱的工作原理、实验室试验及工业应用情况。指出旋流微泡浮选柱工艺指标先进、动力消耗小、节能明显、维护方便 ,是一种从煤泥中回收精煤的高效而经济的工艺设备 ,具有广阔的应用前景     

浮选柱在磷矿选矿中的应用研究

采用浮选柱设备进行磷矿的选矿实验研究。通过化学法分析磷矿的矿物特性,采用浮选柱分选技术,开展磷矿精选试验。结果表明,在充气量为6～10 L/h,冲洗水2～3 L/h可以得到w(P2O5)=30%以上的磷精矿。     

浮选柱中液相轴向返混的研究

An experimental study on the axial dispersion of liquid was carried out in a 0.382-m-ID flotation column packed with different structured packings or free of packings. The correlations of axial Peclet numbers with the liquid and gas superficial Reynolds numbers were developed for various packings. Among the packings tested, it is found that in the column packed with 250Y or 350Y packings the axial dispersion is the lowest. The addition of frother can decrease the axial dispersion. By the simulation analysis of the one-dimension dispersion model of packed flotation column, it is found that small axial dispersion, high collection rate constant and low axial liquid velocity can increase the collection zone recovery.     

磷石膏脱硅柱浮选工艺研究

针对云南高硅磷石膏综合利用的加工特性,研究了磷石膏浮选脱硅柱浮选工艺技术。通过循环压力、浮选液位、捕收剂用量及投矿量的实验获得了较佳的工艺条件,并在此基础上进行了72h连续性实验,获得的精矿中,w(二水硫酸钙)为95.48%、w(SiO_2)为2.53%,精矿产率为85.51%,二水硫酸钙回收率97.98%。     

以精细水煤浆为燃料的局域能源战略

通过精细水煤浆制备的经济分析及其特性介绍，规划设计了精细水煤浆的泵送过程及能源站建设，并分析了其运行的经济性，展示了精细水煤浆作为替代能源的巨大发展潜力。     

Hydrophobic Flocculation Flotation for Beneficiating Fine Coal and Minerals

ABSTRACT

It is shown that hydrophobic flocculation flotation (HFF) is an effective process to treat finely ground ores and slimes so as to concentrate coal and mineral values at a fine size range. The process is based on first dispersing the fine particles suspension, followed by flocculation of fine mineral values or coal in the form of hydrophobic surfaces either induced by specifically adsorbed surfactants or from nature at the conditioning of the slurry with the shear field of sufficient magnitude. The flocculation is intensified by the addition of a small amount of nonpolar oil. Finely ground coals, ilmenite slimes, and gold finely disseminated in a slag have been treated by this process. Results are presented indicating that cleaned coal with low ash and sulfur remaining and high Btu recovery can be obtained, and the refractory ores of ilmenite slimes and fine gold-bearing slag can be reasonably concentrated, leading to better beneficiation results than other separation techniques. In addition, the main operating parameters affecting the HFF process are discussed.     

Application of Statistical Analysis on the Bubble Surface Area Flux in a Column Flotation Cell

Flotation is a widely used separation process with applications from mineral separation to de-inking of recycled paper, waste water treatment, and solid remediation. In flotation column, bubble surface area flux (S_b) has been reported to describe the gas dispersion properties, and it has a strong correlation with the flotation rate constant. No information is available regarding S_b for coal flotation in column cell. This paper describes the effects of hydrodynamic parameters on S_b by means of a 2³ factorial experimental design in designed flotation column using coal slurry. The results showed that S_b increased with increasing superficial gas velocity and frother concentration, but decreased with increasing solid concentration. The main and interaction effects of operating parameters on S_b were evaluated using Yates’ analysis. The statistical model was developed to predict S_b in column flotation cell using experimental data. This paper also presents the development of the statistical model and the validation using a number of additional data sets. There is a good agreement between experimental results and predicted results from the developed model.     

Replacing Mechanical Flotation Cells by a Flotation Column at the Pilot Plant of the Sarcheshmeh Copper Mine

Abstract

A flotation column could be considered as one of the major breakthroughs in the field of mineral processing in the last decades. Due to an increase in the trend of the use of these type of cells in the mineral processing plants, an investigation regarding the performance of these cells was initiated. The flotation column at the Sarcheshmeh pilot plant with some modifications was restarted. When all necessary measures were taken, the possibility of using the flotation cell in the cleaner and recleaner stages was investigated. Replacing the cleaner cells by the column flotation increased the separation efficiency by 7%. When the column cell was used as recleaner and both cleaner and recleaner, an improvement of 10% was observed. It was found that using a column cell instead of mechanical cells in addition to a decrease in repair and maintenance costs could result in 76% and 83% reduction in energy cost of cleaner and cleaner‐recleaner stages, respectively, at the pilot plant.     

浮选技术在煤泥分选中的应用

文章介绍了煤泥浮选技术的原理,概述了浮选药剂和浮选设备的类型和性能,分析了煤泥浮选的工艺条件,并介绍了几种煤泥浮选技术的应用。最后,从浮选药剂的研发、浮选设备的改造、浮选工艺的改进以及浮选技术的创新等方面,对煤泥浮选技术的发展和应用提出了展望。     

Comparison of Internal and External Mixer Spargers in a Laboratory De‐inking Flotation Column

Column flotation has been introduced for waste paper de‐inking to take advantage of low capital cost and excellent separation performance. Bubble generation employs a variety of systems, broadly divided into two types: internal and external. An external in‐line static mixer sparger was tested against an internal porous stainless steel sparger. They were compared in an industrial de‐inking facility using a 10 cm diameter column. Operating conditions were defined and the effect of gas rate, retention time, wash water rate, and froth height on de‐inking was investigated. Both spargers gave similar ink recovery and fiber loss as a function of bubble surface area flux. However, the static mixer gave stable operation while the porous sparger showed evidence of plugging over a 6h test. Combined with some ability to control bubble size, overall the in‐line static mixer gave superior performance.     

一种新型浮选柱的数值模拟及性能研究

自主研制了一种新型多级规整填料浮选柱,应用计算流体力学软件FLUENT6.3.26进行数值模拟计算,对其内部的气液两相流动进行了考察,采用了欧拉-欧拉多相流模型,对气相的模拟采用单一气泡尺寸,液相湍流采用了标准k-ε模型,两相之间的动量传输仅考虑曳力作用。通过模拟,获得了不同实验条件下浮选柱内部的气液速度场分布、气含率分布等,对部分模拟结果进行了定量比较。结果表明随着气相流量的增大,浮选柱内部气含率增大,液体循环速度增大,从而气液之间混合更加充分,这对于提高浮选柱的分选效率和设备的放大有重要意义。在唐山钱家营开滦煤矿选煤厂进行了以其煤浆为原料的浮选性能的测试,在气体1.25 m³/h,进料0.05 L/h条件下20 min停留时间获得了精煤灰分10.28%,尾煤灰分43.39%,精煤产率52.53%的指标,与该厂浮选精煤灰分10.58%相接近。     

高硫煤浮选法脱硫实验研究

采用浮选法脱除贵州某煤中的硫,以磺化煤油为捕收剂,WP溶液为起泡剂,CaO为抑制剂,考察了捕收剂用量、起泡剂用量、抑制剂用量以及矿浆浓度对脱硫率的影响。实验结果表明,在捕收剂用量30kg/t、起泡剂用量1.250kg/t、抑制剂用量37.5kg/t、矿浆质量浓度106g/L的条件下,能有效脱除煤中的硫分,脱硫率达到67.63%。对比分析脱硫前后煤样,结果表明浮选法脱除煤中硫的同时,也提高了煤样的热值,提升了煤的质量。     

聚丙烯酰胺对细粒煤泥浮选和过滤的影响

采用7种型号的聚丙烯酰胺作为添加剂,对西铭煤进行了浮选和过滤试验。结果表明,添加聚丙烯酰胺可以明显提高精煤产率、尾煤灰分,亦可以提高煤泥水澄清度,显著加快过滤速度,降低滤饼水分。其中,非离子型和阴离子型聚丙烯酰胺效果较好。此外,还通过对加药顺序的调整,论证了先加捕收剂后加聚丙烯酰胺的效果比先加聚丙烯酰胺后加捕收剂的效果好。     

旋流微泡浮选柱分选系统的耗散结构分析

基于耗散结构理论,分析了入料因素、操作因素和环境因素对浮选柱分选效果的影响作用,构建了浮选柱分选系统的动力学方程和耗散结构模型,并将该模型应用于选煤生产,实践表明:ω的取值对柱分选系统的熵流模型非常关键,合理的对生产调控具有很大的理论指导意义。     

Study of Oil Removal Kinetics using Cyclone-Static Microbubble Flotation Column

The cyclonic-static microbubble flotation column (FCSMC) has dual effects including the cyclonic separation and airflotation separation with advantages in the oily wastewater treatment field such as the small lower limit of the effective separation size, short separation time, large handling capacity, and low operating cost, especially the polymer-flooding oily wastewater treatment aspect. In this paper, the cyclonic separation function mechanism of the FCSMC was investigated. In addition, several operating parameters which impact oil removal efficiency and kinetics constants such as circulating pressure, the superficial gas velocity and the frother consumption were also investigated. The mathematical model relationship between the separation kinetics constants and the factors including circulating pressure, gas superficial velocity, and the average bubble diameter was established. Based on the strength by steps, the physical separation model of the cyclonic-static microbubble was also established.     

细粒煤全氯乙烯脱灰实验研究

细粒煤全氯乙烯分选是一种新颖的燃前分选工艺。本文采用了全氯乙烯作为溶剂,对石台和七台河煤样进行了分选研究,取得了较好的效果。     

高硫煤浮选脱硫实验研究

采用浮选法研究了磨矿粒度、捕收剂用量、起泡剂用量、抑制剂用量等因素对高硫煤脱硅效果的影响,结果表明,磨矿粒度-200目占48.48%,捕收剂用量1.4kg/t,起泡剂90g/t,抑制剂1.5g/L,浮选时间5min,浮选温度为室温,可获得较好的脱硫效果,脱硫率达到50%左右。论文的研究为高硫煤的浮选法脱硫提供一定的参考依据。     

环流浮选塔用于含油污水处理的实验研究

以空气/含柴油污水为模拟介质体系,在环流浮选塔(外筒体内径100 mm,高932 mm;导流筒内径59 mm,高780 mm)上考察了操作气速、液相流量及浮选塔上部空间填料设置对油-水分离效率的影响. 结果表明,分离效率随操作气速增大先增后降,随液体流量增大而降低;与传统空筒式浮选塔相比,环流浮选塔的分离效率比常规空筒式浮选塔有显著提高. 实验确定的最佳操作气速为0.015~0.02 m/s,最佳液相流量为20 L/h,在环流浮选塔上部设置填料的情况下,油-水分离效率最高可达57.3%. 基于实验数据建立了涉及气泡特性、液相物性、气液相流量及油滴返混影响因素在内的分离效率的经验模型,与实验值吻合较好.     

Flotation of Fine Gold Particles by the Assistance of Coal-Oil Agglomerates

This paper describes the use of coal-oil agglomerates in flotation to increase the gold recovery from an ore containing fine gold particles. The effects of operating parameters on gold flotation recovery such as oil type, particle size of agglomerating material, agglomerate/ore and oil/ore ratios were investigated. The studies showed that petroleum oils are more effective than vegetable oils in oil agglomeration of Kozlu coal and coal-oil assisted gold flotation. Gold recovery can be increased using a higher amount of agglomerates in the process; however, gold grade of the flotation concentrates is reduced significantly. The use of bridging oil at high concentrations in the agglomeration process provides high-grade gold concentrates, but lower recoveries. The utilization of coarser coal particles in the coal-oil agglomeration stage leads to higher selectivity and recovery values for gold particles.